Materials for electroluminescent devices

Abstract

Materials containing one or more borazine rings are employed as materials for electroluminescent devices. The compounds have molecular structures represented by the following formula: in which R 1 –R 6 are independently a metal; a whole or part of an optionally substituted borazine ring; hydrogen; halogen; hydroxyl; optionally substituted alkyl, cycloalkyl, aryl, acyl, alkoxy, acyloxy, amino, acylamino, aralkyl, cyano, carboxyl, thio, vinyl, styryl, aminocarbonyl, carbamoyl, aryloxycarbonyl, phenoxycarbonyl, or alkoxycarbonyl, as well as recognized donor and acceptor groups. The compounds have high thermal stability as well as hole and electron mobilities.

1. An electroluminescent device comprising an electroluminescent material sandwiched between electrodes, wherein the electroluminescent material comprises at least one borazine-containing entity represented by formula I, 
       
         
           
           
               
               
           
         
       
       wherein R 1 –R 6  are independently selected from the group consisting of metal; an optionally substituted borazine ring; hydrogen; halogen; hydroxyl; unsubstituted or substituted alkyl group, cycloalkyl group, aryl group, acyl group, alkoxy group, acyloxy group, amino group, acylamino group, aralkyl group, cyano group, carboxyl group, thio group, vinyl group, styryl group, aminocarbonyl group, carbamoyl group, aryloxycarbonyl group, phenoxycarbonyl group, and alkoxycarbonyl group, with the substituents being selected from the group consisting of metals, hydrogen, halogen, hydroxyl, donor groups and acceptor groups; and wherein the substituents together with the group on which they are substituted can form a ring. 
     
     
       2. The electroluminescent device according to  claim 1 , wherein the R 1  to R 6  groups of the borazine-containing entity are independently selected from the group consisting of hydrogen, phenyl, diphenyl, diphenylamino, C 1-4  alkyl, and naphthyl or adjacent groups are linked so as to form a ring. 
     
     
       3. The electroluminescent device according to  claim 2 , wherein R 1 , R 3  and R 5  of the borazine-containing entity are the same and R 2 , R 4  and R 6  are the same. 
     
     
       4. The electroluminescent device according to  claim 3 , wherein one of R 1  and R 2  of the borazine-containing entity is hydrogen and the other is phenyl or diphenylamino. 
     
     
       5. The electroluminescent device according to  claim 3 , wherein one of R 1  and R 2  is methyl and the other is phenyl, diphenyl, diphenylamino or naphthyl. 
     
     
       6. The electroluminescent device according to  claim 1 , wherein the borazine-containing entity is disposed in at least one layer selected from the group consisting of hole-injection layer, hole-transporting layer, electron-injection layer, electron-transporting layer, emissive layer comprising a single emitter or host with one or more emissive dopant(s), hole-blocking layer and electron-blocking layer. 
     
     
       7. The electroluminescent device according to  claim 6 , wherein the hole transporting layer comprises the borazine-containing entity. 
     
     
       8. The electroluminescent device according to  claim 7 , wherein the R 1  to R 6  groups of the borazine-containing entity are independently selected from the group consisting of hydrogen, phenyl, diphenyl, diphenylamino, C 1-4  alkyl, and naphthyl or adjacent groups are linked so as to form a ring. 
     
     
       9. The electroluminescent device according to  claim 8 , wherein R 1 , R 3  and R 5  of the borazine-containing entity are the same and R 2 , R 4  and R 6  are the same. 
     
     
       10. The electroluminescent device according to  claim 9 , wherein one of R 1  and R 2  of the borazine-containing entity is hydrogen and the other is phenyl or diphenylamino. 
     
     
       11. The electroluminescent device according to  claim 9 , wherein one of R 1  and R 2  is methyl and the other is phenyl, diphenyl, diphenylamino or naphthyl. 
     
     
       12. The electroluminescent device according to  claim 7 , wherein R 1 , R 3  and R 5  of the borazine-containing entity are the same and are substituted or unsubstituted phenyl and R 2 , R 4  and R 6  are hydrogen. 
     
     
       13. The electroluminescent device according to  claim 7 , wherein the borazine is 1,3,5-triphenylborazine. 
     
     
       14. The electroluminescent device according to  claim 1 , wherein the device has a single layer between the electrodes. 
     
     
       15. The electroluminescent device according to  claim 1 , wherein the device has two layers between the electrodes. 
     
     
       16. The electroluminescent device according to  claim 1 , wherein the device has more than two layers between the electrodes. 
     
     
       17. The electroluminescent device according to  claim 1 , wherein the electroluminescent material comprises an emitting layer which comprises an emitter and a host therefore in which the host comprises the borazine-containing entity. 
     
     
       18. The electroluminescent device of  claim 1  incorporated in a flat panel display. 
     
     
       19. The electroluminescent device of  claim 1 , wherein the electroluminescent material comprises an emitting layer containing tris(8-hydroxyquinoline) aluminum or 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene).